This Bugzilla instance is a read-only archive of historic NetBeans bug reports. To report a bug in NetBeans please follow the project's instructions for reporting issues.
I've run a code, which finds or instantiates a package in one thread and fills it with instances in another one. To my surprise, code which creates instances within (already createad) package extent interfered with the code which was iterating through package extents in the Repository trying to find a specific extent. The operations are quite unrelated (to a client), so the ConcurrentModEx seems more like implementation/design bug. Attaching a stacktrace.
Created attachment 4582 [details] Exception's stacktrace
During discussion with Martin about this issue an interesting thing came out: Suppose you'll have two classes C connected by an association A in the metamodel. Now suppose there are instances of C (a, b, c, d, e) connected as a -> b and c -> d. If the client code now retrieves link collection with endpoint "c" trying to iterate through the collection and some other thread is changing a -> b to e.g. a->e, the iterating client will get the ConcurrentModEx. This is quite unusual and unexpected for the client, since nothing has interfered with the link set being iterated.
Fixed in main trunk.
quite for too long, verified